You can get Uub and Gotenks. I don't remember how to get Gotenks, but you get Uub like this: on Goku's DU, on the last fight against kid Buu, get him down to his last bar, then, while in normal state (no super saiyan), use Spirit Bomb to defeat him. But you have to win the Ultimate Attack Game thingy. Goku should say "haha, You were great! I can't wait until next time! So long!" Afterwards you'll fight Uub at the world tournement. Beat him to get his capsule.